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Year 4 - Psychiatry > Antidepressants > Flashcards

Antidepressants Flashcards

1
Q

What are the main types of antidepressants?

A
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Serotonin and noradrenaline reuptake inhibitors (SNRIs)
  • Tricyclic antidepressants (TCAs)
  • Others (mirtazapine and vortioxetine)
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2
Q

How do SSRIs work?

A

Block the reuptake of serotonin by the Presynpatic membrane on the axon terminal

Causes more serotonin in the synapses in the CNS, boosting communication between neurones

Can lead to down-regulation of post-synaptic serotonin receptors

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3
Q

How do SNRIs work?

A

Blocking the reuptake of serotonin and NorAd by the presynaptic membrane

More serotonin and NorAd in synapses in the CNS

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4
Q

How do Tricyclic antidepressants work?

A

Block reuptake of serotonin and NorAd by presynaptic membrane

Block ACh and histamine receptors giving them anticholinergic and sedative side effects

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5
Q

What are the common ACh (muscarinic) effects?

A
  • Dry mouth
  • Thirst
  • Difficulty urinating
  • Urinary retention
  • Dry skin
  • Hot and flushed skin
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6
Q

What are the common Histamine effects?

A
  • Dry mouth
  • Drowsiness
  • Dizziness
  • Nausea and vomiting
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7
Q

What are the common Adrenaline/NorAd effects?

A
  • Sweating
  • Tremor
  • Headaches
  • Nausea
  • Dizziness
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8
Q

What are some examples of SSRIs?

A

Sertraline
Citalopram
Escitalopram
Fluoxetine
Paroxetine

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9
Q

Outline sertraline

A

Anti-anxiety effects

Considered one of the safest in patients with heart disease

Higher rate of diarrhoea

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10
Q

Outline citalopram

A

Can prolong QT interval (dose dependent)

QT prolongation can cause torsades de pointes

Along with escitalopram, least safe SSRI in patients with heart disease (still safer than TCAs)

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11
Q

Why is fluoxetine the first-line choice in children and adolescents?

A

Long half-life of 4-7 days
Remains active in the body long after stopping

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12
Q

What can paroxetine cause?

A

Weight gain
Discontinuation symptoms

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13
Q

What are the key side effects of SSRIs?

A

GI symptoms
Headaches
Sexual dysfunction
Hyponatraemia
Anxiety or agitation
Increased suicidal thoughts, suicide risk, self-harm
Increased bleeding risk (especially with anticoags or NSAIDs)

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14
Q

What are some examples of SNRIs?

A

Duloxetine
Venlafaxine

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15
Q

What are some side effects of SNRIs?

A

Similar to SSRIs

Increased blood pressure

Contraindicated in uncontrolled hypertension

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16
Q

When is venlafaxine used?

A

Inadequate response to other antidepressants

  • More likely to cause discontinuation symptoms when stopped
  • Increased risk of death from O.D
  • Must measure blood pressure
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17
Q

What are some examples of TCAs?

A

Amitriptyline
Nortriptyline

Used at low dose for neuropathic pain (this dose is too low to treat depression)

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18
Q

What are TCAs known to cause?

A

Arrhythmias e.g.
- Tachycardia
- Prolonged QT interval
- Bundle branch block
- Dry mouth
- Urinary retention

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19
Q

What should patients be warned about when taking TCAs?

A

Blurred vision espeically if they drive or operate heavy machinery

Due to antimuscarinic properties of TCAs

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20
Q

Why are TCAs taken at night?

A

Due to its anticholinergic effects it also causes sedation

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21
Q

What are the side effects of Mirtazapine?

A

Sedation
Increased appetite
Weight gain

Taken at night due to sedative effect
(Greatest effect at low doses e.g. 15mg, less present at high doses e.g. 45mg)

Less likely to cause sexual dysfunction

22
Q

How does mirtazapine work?

A

5HT-2 and 5HT-3 antagonist
Strong H1 activity- causes the sedation

23
Q

How can side effects be beneficial to different patients? e.g. Mirtazapine

A

If a patient is struggling to sleep, with weight loss then the side effects causing sedation and increased appetite can be helpful for the patient

This is why mirtazapine is more useful in older patients, however, in overweight oversleeping patients it is not useful

24
Q

When is vortioxetine used?

A

Third-line treatment after inadequate response to two other antidepressants

Acts as SSRI and also stimulates and blocks various types of serotonin receptors

Considered safe with heart disease, commonly causes nausea for first few weeks

25
Q

What are monoamine oxidase inhibitors?

A

MAOI-A, works on serotonin break down enzymes, so there is an increase in serotonin in the terminal
MAOI-B, works on dopamine break down enzymes, increase in dopamine in the terminal

Both can cause an increase in adrenaline

26
Q

When are MAOIs favoured?

A

Atypical depression

27
Q

What are some examples of irreversible MAOIs?

A

Phenelzine
Isocarboxazid

More dangerous

28
Q

What are some examples of reversible MAOIs?

A

Moclobamide
Tranylcypromine

Less dangerous

29
Q

What must be considered when giving MAOIs?

A
  • Potential for significant and dangerous interactions with other drugs
  • Tyramine reaction leading to hypertensive crisis
30
Q

What must be avoided to prevent a tyramine reaction?

A

Cheese
Pickled meats
Wine

31
Q

How can you change MAOIs to another antidepressant?

A

6 week washout period

32
Q

What is the most common side effect of vortioxetine?

A

Nausea

33
Q

When is vortioxetine used?

A

Difficult to treat cognitive symptoms

34
Q

What can occur in the period of starting an antidepressant?

A

Increased :
- Agitation
- Anxiety
- Suicidal thoughts
- Acts of suicide

Particular problem in younger patients

35
Q

When should patients be reviewed after starting antidepressants?

A

18-25
Within one week (due to increased risk of suicide)

Over 25
Within two weeks

Normally a noticeable response within 2-4 weeks of treatment, with inadequate response the next step is to consider increasing dose or changing treatment

36
Q

When starting treatment for depression for the first time, when should an SNRI be considered?

A

Comorbid neuropathic pain

37
Q

In depression when do you increase or switch antidepressants?

A

No benefit- switch

Partial benefit - increase dose

38
Q

In anxiety when do you increase or switch antidepressants?

A

Increase dose if no initial benefit

39
Q

What antidepressants can be directly switched?

A

SSRIs and SNRIs (except fluoxetine due to long half-life)

40
Q

How do you switch between an SSRI and other antidepressants e.g. mirtazapine?

A

Cross-tapered over several weeks

Gradually reducing dose of existing drug while increasing dose of new one

41
Q

What can happen if antidepressants are stopped too suddenly?

A

Once started they should be continued for at least 6 months before stopping (2 years in recurrent depressing)

Stopping too early can cause depression to return

42
Q

How should antidepressants be stopped?

A

Dose should be slowly reduced over at least 4 weeks to minimise discontinuation symptoms

43
Q

What are discontinuation symptoms?

A

2-3 days after stopping treatment

Resolves within 1-2 weeks

Flu-like symptoms
Electric shock-like sensations
Irritability
Insomnia
Vivid dreams

44
Q

What influences discontinuation syndrome?

A

Half-life

Shorter half-life, bigger the problem

45
Q

What medications are the most responsible for discontinuation syndrome?

A

Paroxetine
Venlafaxine

46
Q

How can you deal with discontinuation syndrome?

A

Alternate days or taking
Snap tablets in half

If very difficult, switch to fluoxetine, then reduce and stop that

47
Q

What is serotonin syndrome?

A

Mild to severe and potentially life-threatening symptoms

Caused by excessive serotonin activity

Usually occurs with higher doses of antidepressants and when multiple are used together

48
Q

What are the symptoms of serotonin syndrome?

A

Altered mental state
- Anxiety
- Agitation

Autonomic nervous system hyperacitivty
- Tachycardia
- Hypertension
- Hyperthermia

Neuromuscular hyperactivity
- Hyperreflexia
- Tremor
- Rigidity

49
Q

Why is severe serotonin syndrome a medical emergency?

A
  • Confusion
  • Seizures
  • Severe hyperthermia
  • Respiratory failure
50
Q

How is severe serotonin syndrome treated?

A
  • Supportive care e.g. benzodiazepines for sedation
  • Withdrawal of causative medications
  • Aggressive fluid treatment
  • Cryptoheptadine
51
Q

In alcoholic dependents with serotonin syndrome why do you give pabrinex first before glucose?

A

Thiamine is a cofactor for glucose metabolism

So when glucose is broken down this increases thiamine deficit, worsening thiamine deficiency

Year 4 - Psychiatry (23 decks)

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